Rocket stove or gasifier + biochar?

Foraging for information... and I stumbled on the gasifier!
It happened that I wanted to make char, now I call it biochar!
We can be carbon negative by heating up with little smoke + giving back the carbon to the soil.

I have not seen any for heating but for cooking, and models adapt to what is available for burning.
Of lot of stuff about biochar and terra preta can also be found on Internet.
A rocket stove makes biochar too, but burns it readily!

I need mainly cooking, as I am in a warm area.
I need a little heat though sometimes...
and hot water too...
I want to make biochar, but I do not want to loose the gas and the energy.
No burning for burning!

Any idea also if it could be possible to heat with the woodgas?
The advantage over the rocket stove is to make biochar...

Hi Tim, happy to see at least one other person can share my search!
What do you want to do appart form biochar? Barbecue? Some cooking?

At the moment I am stuck to mix the system, because in a rocket, the hot fire and the internal chimney in the barrel are PUSHING the gases, so they can go into the pipes and release their heat into the mass. In a "normal" stove, the smoke is not pushed but the outside attracts the smoke out.

In the pyrolysis system, I do not see how the fire can push the gases out and how we can use the heat.

So I might do a rocket for the weeks I will need heating, and I will do a gasifier for cooking and also for water heating. Here where I am, thinking along the way...

I have been brainstorming how to efficiently make biochar. The TLUD seems rather inefficient as so much fuel is burned to heat the retort.

I have not tried any of this yet as I just put it onto paper yesterday, but here goes.

construct an outdoor rocket mass heater with the following differences:
1. instead of (or perhaps on top of) the big bell (heat riser) that radiates heat, place an old iron woodstove (or any sort of sealable durable metal container) that would function as the retort.
2. There could be a wood gas exhaust line (from the retort) with multiple valves to allow distribution to mulitiple useful ends (internal combustion electrical generator, cookstove, down into the rocket...)
3. The insulating mass would cover the entire apparatus with moveable insulation for the retort door.
4. no long warming bench for the rocket exhaust. Place heat exchanger fins under the retort in the heat riser chamber, to extract as much heat from the exhaust as possible.

I am only imagining how this would work from listening to podcasts and reading articles. But with the technicalities worked out and much experimentation I think that it could be a much more efficient means of producing biochar and usable wood gas for the homestead.

Here are a couple childlike drawings that I made during an HR meeting at work, lol.

C Hopper wrote:I have been brainstorming how to efficiently make biochar. The TLUD seems rather inefficient as so much fuel is burned to heat the retort.

1. instead of (or perhaps on top of) the big bell (heat riser) that radiates heat, place an old iron woodstove (or any sort of sealable durable metal container) that would function as the retort.

I think there is no fuel burning the retort in a TLUD, as only what is inside is burning, no outside fire.
With the rocket you drew, the fire heat some wood to make char, and then it uses some extra fuel.

The only problem I see with the real TLUD is the difficulty to start the fire inside. It is usually made with some petrol product...
Then, I do see how to use the TLUD for cooking, but not for heating, and not for pushing the heat and smokes like the rocket stove.

As recent grad of Ernie and Erica (s) work shop My 1st build is off in the future, however I have been following Biochar/black earth for years and have watched the amount of charcoal of all types that local nurseries are Now using ! I am convinced that producing biochar in a Rocket Stove is possible, consider Ionto Evans book on Rocket Stoves reports on a R.S. used as a kiln to kiln dry wood commercially , also consider that the combustion air at the top of the R.S. s 55 gal drum,Should have consumed All of the Oxygen at that point. Recovery of wood gasses driven of at this point (in an Oxygen deficient Environment ) While not easy should be possible ,allowing for the gasses reuse, possibly at a distant point and the biochar should be of the highest quality with little lost to nonexistant Oxydation ! Best Allen L.

If you want to produce biochar using a heating or cooking rocket stove, just build in a grate and quenching bath below the main biomass burning area as the biomass chars some of the material will drop through the grate and into the water bath interrupting the combustion and producing a useful biochar for your garden.

Some % yes, but water is 100%!
Did you try it and did you have condensation?

I just considered the fact that it is said that the drier the better for the wood!
It is even supposed to be more important than for other stoves.
And condensation in the pipes is an issue in RMH, because of the colder smoke.

Xisca Nicolas : I thought i did ! I sent an answer to the Oxygen deficient atmosphere Question you asked Last Oct , but it didn't post ? SORRY !!!

After the primary wood burning that occurs in the burn tunnel, the second one occurs within the Heat Riser and at the top of the barrel where the gases churn and remix, before cooling and leaving the barrel !

It has been noted that after 20 years of seasonal operation All of the original 55gal barrels on The 1st Rocket stoves was/are still intact, i.e. had not burned/rusted out. There is two best guesses as to how this happened !

One idea is that at the point that the gases reach the barrel all but a trace of the free un-bound Oxygen has in fact been bound-up in heat producing reactions, further reactions occur producing CO2 and H2O which are non-reactive!

Said another way the oxygen is still there, it has not been destroyed, it just can not be part of any more reactions ( or new alliances ) This is the Oxygen deficient environment i was talking of .

Wood baked in such an environment will out-gas without combustion occurring to consume the charcoal, the wood gases driven off must be used for their useful energy content otherwise you are adding to pollution.

Its obvious, but it must be said. It can be channeled into the burn tube to burn-up and add to energy stored in the thermal cob !

There is a 2nd idea of why the barrel lasts so long, and that is that any un-bound oxygen is combining by preference with the hotter exhaust gases saving the barrel.

It is still generally held to be true that at the point the exhaust gases leave the barrel they are inert , incapable of sustaining any more combustion ! Y.M.M.V , - PYRO - AL sorry this is so late !

It took me to read some sentences to understand you were not talking about the subject of the charcoal dropping down into water, but then I got it!
Don't be sorry as I will not excuse you anyway (lol!) but I thank you!
I owe you to read again and understand better, as this is not obvious for me.
I will not loose your precious explanations.

I am going slowly into the project and I convince little by little some people here about the usefulness and advantages of a RMH.
I need to understand so that I can help the making (as I am not able to do it...) with the measures, shape and so on.

Many people have no stove here, as we are frost-free...
But now, we drop down to under 40°F after sunset...
And winter is the wet season.

Thanks Chelle for this, very clever design!
Nevertheless I think I have a problem with gasifier or this stove too, I cannot get wood chips or anything small.
I have only branches and do not use machines to brake them down.
The advantage of rockets for me is very much that I can cut my wood myself with my pair of Fiskars!!
I do not have enough almonds shells either, nor any cereal bran...

So, how can I make biochar with branches...? don't even know if this is possible because of the difficulty to start the fire and to maintain it if there is a lot of air in the mix...

The video shows a gasifier stove being used to create biochar. The gasses from the biochar chamber are then distilled into various synthetic fuels, some of which are used to power and electrical generator and a fridge:
http://www.youtube.com/watch?v=_o5M6v1eD4I

Would it work to pyrolize that wood in the back-side of the burn chamber of a normal rocket-mass stove? I am thinking if you fill 1/3 or of the side where the wood comes in (leaving a gap right where the intake/combustion chamber are), the heat will go past that wood, and flow toward the outlet. The charcoal can then char with a reduced amount of oxygen and maximal heat inside the re-burn chamber (but off to the side of the main heat and air flow). Does this make sense?

There is no "out-of-the-way" space in the combustion zone of a RMH; anything in there will be completely consumed.

But it might be possible to make a separate chamber perhaps on top of the burn tunnel, which can be loaded with wood from outside and then sealed with an insulated cover. Small slots opening to the burn tunnel or heat riser would allow gases given off to enter the combustion zone and contribute directly to heating, while fresh oxygenated air would be kept out of the char box. It would take experimentation to see how much biomass could be charred at a time, how long it takes relative to the length of a typical RMH burn, how close the char box needs to be to the combustion zone so as to be heated enough...

There a couple of designs floating around where the burn tunnel is "insulated" with a jacket filled with wood chips.
The heat pyrolizes the chips,the wood gas is directed into the burn chamber or riser. Alternatively, I have seen a retort set right above the top of the riser, with the gasses directed back into the burn chamber via black iron pipe.
It occurs to me that any rocket stove design that has a " white oven " incorporated, could have that oven changed into a retort by the adding a way for wood gass to be routed from the top of the oven back to some part of the rocket.
To me the best reason for making charcoal is to use it in a charcoal gasifier feeding a internal combustion engine.
When it comes to gasifier, making charcoal is effectively a refining wood into a form that stores better an burns more cleanly, in a simpler system.
If you can utilize the heat released during charcoal making , the wood gasses are not wasted.

I had the idea that perhaps you could create an additional enclosure around the barrel of your rocket heater, and gasify wood with the heat produced, then you could feed the gas into the burn chamber.
I've attached a picture to demonstrate.
I think the biggest challenge with this approach would be to ensure the exhaust temperature was still low enough. Possibly adding fins between the shroud and barrel would allow more heat to be pulled out.

Gasifying-Rocket-Stove.png

Charcoal making with a rocket heater

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